This invention relates generally to turbine engines and, more specifically, to nozzle assemblies used with turbine engines.
At least some known turbine engines include a variable exhaust nozzle system, such as is typical of supersonic military aircraft. The variable exhaust nozzle system enables the geometry of the exhaust system to selectively change. More specifically, variable geometry systems are configured to operate over a wide range of pressure ratios by adjusting a nozzle throat based on the demands of the engine cycle, and adjusting a nozzle area ratio to facilitate achieving a desired engine performance at various operating points.
At least one known engine includes a fixed exhaust nozzle system that facilitates enhanced engine performance through adjustments to a plurality of flow path liners spaced circumferentially about the exhaust nozzle such that the liners partially define such assemblies, the flow path liners are coupled via a plurality of connections to a structural member within the engine or fuselage, such as a duct. Because of the thermal expansion, flow path liners are generally loosely supported and may be difficult to adjust. To facilitate reducing discontinuities between liner sections and to facilitate maintaining a desired flow path contour, at least some exhaust nozzles include the use of a plurality of shims.
At least some known shims include peelable layers having an adhesive applied to an outer surface thereof for positioning within the nozzle assembly. The peelable layers are removed to adjust the thickness of the shim. This shim is positioned within the nozzle assembly for adjusting the liner geometry. Additionally, at least some known shims are loose stackable washers that are positioned within the nozzle assembly for adjusting the flow path contour. However, coupling mechanisms used with such shims may become ineffective during engine operation because of exposure to high temperatures, or because of being subjected to side loading or motion. As such, the shims may fall to the lowest level of the nozzle assembly during assembly or disassembly. Accordingly, adjustments to the nozzle assembly may be a time consuming task. Adjustable height bushings facilitate alleviating fit-up issues with known bushings. Some known adjustable height bushings require a large envelope to incorporate them into the nozzle assembly. Additionally, such bushings add significant cost and weight to the exhaust system. If the fittings are not in the necessary locations when assembly of the supporting structure is attempted, retrofit of the adjustable height features is unlikely to be feasible.